Vulnerability-Lookup

GHSA-F5P7-25H5-XXWH

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_fib: reject fib expression on the netdev egress hook

A fib expression in a netdev egress base chain dereferences nft_in(pkt), NULL on the transmit path, causing a NULL pointer dereference at eval. nft_fib_validate() masks the hook with NF_INET_* values, but netdev hook numbers are a separate enum that aliases them (NF_NETDEV_EGRESS == NF_INET_LOCAL_IN), so an egress chain passes validation and then faults.

Add nft_fib_netdev_validate() that limits each result/flag to the netdev hook where the device it reads exists: the input-device cases (OIF, OIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE with F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict nft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are not applied to another family's hooks.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72254"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:52Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_fib: reject fib expression on the netdev egress hook\n\nA fib expression in a netdev egress base chain dereferences nft_in(pkt),\nNULL on the transmit path, causing a NULL pointer dereference at eval.\nnft_fib_validate() masks the hook with NF_INET_* values, but netdev hook\nnumbers are a separate enum that aliases them (NF_NETDEV_EGRESS ==\nNF_INET_LOCAL_IN), so an egress chain passes validation and then faults.\n\nAdd nft_fib_netdev_validate() that limits each result/flag to the netdev\nhook where the device it reads exists: the input-device cases (OIF,\nOIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE\nwith F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict\nnft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are\nnot applied to another family\u0027s hooks.",
  "id": "GHSA-f5p7-25h5-xxwh",
  "modified": "2026-08-17T06:33:19Z",
  "published": "2026-08-15T06:32:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72254"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4fee43759b489559a491f7c95f9bfa7a1d0c7a10"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/568931f26af4727a51e8521f72efbc78d3b82410"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d01c913febead04a01a5f3a6374d1f45504dc523"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d07955dd34ecae17d35d8c7d0a273a3fba653a8c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f68305267ebda7e839b5e8f77e8d77535a3d5a0f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72254 (GCVE-0-2026-72254)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-17 05:42

Title

netfilter: nft_fib: reject fib expression on the netdev egress hook

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_fib: reject fib expression on the netdev egress hook A fib expression in a netdev egress base chain dereferences nft_in(pkt), NULL on the transmit path, causing a NULL pointer dereference at eval. nft_fib_validate() masks the hook with NF_INET_* values, but netdev hook numbers are a separate enum that aliases them (NF_NETDEV_EGRESS == NF_INET_LOCAL_IN), so an egress chain passes validation and then faults. Add nft_fib_netdev_validate() that limits each result/flag to the netdev hook where the device it reads exists: the input-device cases (OIF, OIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE with F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict nft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are not applied to another family's hooks.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Assigner

Linux mitre root

References

5 references

URL	Tags
https://git.kernel.org/stable/c/4fee43759b489559a…
https://git.kernel.org/stable/c/568931f26af4727a5…
https://git.kernel.org/stable/c/d01c913febead04a0…
https://git.kernel.org/stable/c/f68305267ebda7e83…
https://git.kernel.org/stable/c/d07955dd34ecae17d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 , < 4fee43759b489559a491f7c95f9bfa7a1d0c7a10 (git) Affected: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 , < 568931f26af4727a51e8521f72efbc78d3b82410 (git) Affected: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 , < d01c913febead04a01a5f3a6374d1f45504dc523 (git) Affected: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 , < f68305267ebda7e839b5e8f77e8d77535a3d5a0f (git) Affected: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 , < d07955dd34ecae17d35d8c7d0a273a3fba653a8c (git)
Linux	Linux	Affected: 5.16 Unaffected: 0 , < 5.16 (semver) Unaffected: 6.6.148 , ≤ 6.6.* (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_fib.c",
            "net/netfilter/nft_fib_netdev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4fee43759b489559a491f7c95f9bfa7a1d0c7a10",
              "status": "affected",
              "version": "42df6e1d221dddc0f2acf2be37e68d553ad65f96",
              "versionType": "git"
            },
            {
              "lessThan": "568931f26af4727a51e8521f72efbc78d3b82410",
              "status": "affected",
              "version": "42df6e1d221dddc0f2acf2be37e68d553ad65f96",
              "versionType": "git"
            },
            {
              "lessThan": "d01c913febead04a01a5f3a6374d1f45504dc523",
              "status": "affected",
              "version": "42df6e1d221dddc0f2acf2be37e68d553ad65f96",
              "versionType": "git"
            },
            {
              "lessThan": "f68305267ebda7e839b5e8f77e8d77535a3d5a0f",
              "status": "affected",
              "version": "42df6e1d221dddc0f2acf2be37e68d553ad65f96",
              "versionType": "git"
            },
            {
              "lessThan": "d07955dd34ecae17d35d8c7d0a273a3fba653a8c",
              "status": "affected",
              "version": "42df6e1d221dddc0f2acf2be37e68d553ad65f96",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_fib.c",
            "net/netfilter/nft_fib_netdev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.16"
            },
            {
              "lessThan": "5.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.148",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.101",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_fib: reject fib expression on the netdev egress hook\n\nA fib expression in a netdev egress base chain dereferences nft_in(pkt),\nNULL on the transmit path, causing a NULL pointer dereference at eval.\nnft_fib_validate() masks the hook with NF_INET_* values, but netdev hook\nnumbers are a separate enum that aliases them (NF_NETDEV_EGRESS ==\nNF_INET_LOCAL_IN), so an egress chain passes validation and then faults.\n\nAdd nft_fib_netdev_validate() that limits each result/flag to the netdev\nhook where the device it reads exists: the input-device cases (OIF,\nOIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE\nwith F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict\nnft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are\nnot applied to another family\u0027s hooks."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Once a netdev egress fib rule is installed, evaluation runs on the packet transmit datapath (nf_hook_egress in __dev_queue_xmit); a remote peer can trigger it by causing the host to send matching IPv4/IPv6 traffic through the hooked interface, matching prior netfilter CNA treatment of pre-deployed nftables rules (e.g. CVE-2026-52998).\nAC:L - No race or uncontrollable victim state is required; with an affected egress fib rule present, the attacker reliably triggers the NULL dereference on the next matching outbound packet by controlling protocol headers and normal connection traffic.\nPR:N - Runtime exploitation needs only network traffic through the netdev egress hook; although installing the fib rule requires CAP_NET_ADMIN, validation incorrectly accepts it as legal, so orchestration or administrators can deploy it and remote attackers need no target credentials or local privileges.\nUI:N - No victim interaction is required beyond ordinary network traffic processing; the kernel automatically evaluates the fib expression on egress without mounts, file opens, or user prompts.\nS:U - Impact is a kernel NULL-pointer fault and host-wide denial of service within the same kernel/network-filtering security authority; it does not constitute VM escape, IOMMU bypass, or another cross-authority boundary change.\nC:N - The failure mode is a NULL pointer dereference of nft_in(pkt) on egress (in is NULL in nf_hook_state_init); there is no use-after-free, out-of-bounds read, or other attacker-controlled memory disclosure primitive.\nI:N - The bug does not corrupt writable memory or provide control-flow hijack; it only dereferences a NULL input device pointer during fib lookup/skipping and cannot modify kernel or user data beyond the immediate fault.\nA:H - The NULL dereference in nft_fib_netdev_eval/nft_fib4_eval/nft_fib6_eval on netdev egress causes a kernel oops/panic-class fault during packet transmission, denying system availability until reboot."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:42:07.408Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4fee43759b489559a491f7c95f9bfa7a1d0c7a10"
        },
        {
          "url": "https://git.kernel.org/stable/c/568931f26af4727a51e8521f72efbc78d3b82410"
        },
        {
          "url": "https://git.kernel.org/stable/c/d01c913febead04a01a5f3a6374d1f45504dc523"
        },
        {
          "url": "https://git.kernel.org/stable/c/f68305267ebda7e839b5e8f77e8d77535a3d5a0f"
        },
        {
          "url": "https://git.kernel.org/stable/c/d07955dd34ecae17d35d8c7d0a273a3fba653a8c"
        }
      ],
      "title": "netfilter: nft_fib: reject fib expression on the netdev egress hook",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72254",
    "datePublished": "2026-08-15T05:54:42.239Z",
    "dateReserved": "2026-08-09T03:40:39.915Z",
    "dateUpdated": "2026-08-17T05:42:07.408Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-F5P7-25H5-XXWH

CVE-2026-72254 (GCVE-0-2026-72254)

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Sightings

Nomenclature